Star sensor fails, Chandrayaan 1 in trouble

Bangalore: Less than a year after its high profile launch, India's ambitious moon mission Chandrayaan I has developed a serious snag. The failure of the lunar craft's altitude sensor has forced ISRO to push its orbit from 100 kilometers to 200 kilometers from the moon's surface. The change in orbit means the data would be of lower quality.

ISRO Chairman, G Madhavan Nair explained the problem saying, "One of the prime sensors which determines altitude has failed. It is called the star sensor."

"We had to make a judicious judgement - how much to gain further and whether we want to take any further risk on the life of the spacecraft. So we raised it," he added about pushing the orbit further out.

The current task for Chandrayaan 1 is to study the moon through high resolution images, mineral mapping and X-rays.

The glitch in the star sensor basically means that the manouvering that was done automatically on the Chandrayaan craft will now have to be done manually from the ground station - which means more monitoring and more time. But unperturbed by this setback, ISRO scientists say they'll continue to try more experiments with it, specially during the solar eclipse next week.

Programme Director, M Krishnaswamy says, "We wanted to monitor shadow movement. Many people are observing the craft from the ground. We wanted to see the image of the shadow passing and how it's moving from the moon's orbit."

But scientists point out that the glitch is also a boon in disguise. The sensor may have failed due to solar radiation and that has taught ISRO valuable lessons for Chandrayaan II.

Chandrayaan I is likely to be complete all its tasks within the next four to five months after which ISRO may even decide to allow the craft to decay and fall apart, rather than maintain it till October 2010, as initially planned.